There is increasing interest in using high bandwidth Dynamic Random Access Memory (DRAM) technology in graphics systems. The Graphics Double Data Rate 3 (GDDR3) specification is a DRAM memory specification that utilizes on-die termination to improve signal quality and thereby also permit higher memory clock rates. GDDR3 is described in the articles by Chris Johnson, “The Future of Memory: Graphics DDR3 SDRAM Functionality,” Designline, Vol. 11, issue 4, 4Q02 and “Graphics DDR3 On-Die Termination and Thermal Considerations,” Designline Vol. 12, issue 1, 1Q03/2Q03, the contents of each of which are hereby incorporated by reference. The on-die termination may be implemented using a push-pull driver circuit to set a termination resistance at the end of a transmission line using a pull-up resistor to a high voltage VDDQ. This permits, for example, a GDDR3 memory to operate at higher memory clock data rates than previous generation technologies, such as DDR. However, the on-die termination of GDDR3 has an associated DC current path from the termination to ground such that on-die termination results in increased on-die DC current and power dissipation compared with slower-speed technologies such as DDR. As a result, while GDDR3 offers improved signal quality and higher speeds. the cost of the using the on-die termination is that there is increased on-chip power dissipation associated with the on-die termination. Additionally, the use of higher clock rates in a graphics system also increases power consumption and heat dissipation.
The improved signal quality and memory clock rates of GDDR3 are beneficial for graphics systems implemented as set-top boxes. However, a problem arises in applications, such as notebook computers, where there is a power budget or a thermal budget. In such applications. utilizing a conventional GDDR3 memory may be undesirable.
Therefore, in light of the above described problems the apparatus, system. and method of the present invention was developed.